This study examined the perception of one's own and others' ability in preschool Japanese boys and girls. In Study 1, 70 Japanese boys and girls aged 4–6 years rated their own and their close friend's ability on their favorite outdoor and indoor activities. In Study 2, 65 Japanese children aged 5 and 6 years rated their own and their close friend's ability and guessed that of a nonfriend (a mere acquaintance child in the preschool) on their most and least favorite outdoor and indoor activities. The major findings were as follows: (a) the perception of preschool children's own ability correlates with that of their close friend's ability; (b) ability perception was influenced by preference for the activity and by gender; and (c) no difference was found between ratings for a close friend and a nonfriend according to activities preferences, which differed from the ability perception by preadolescent children.